Process for recycling a metalized polyester film

ABSTRACT

The present invention relates to a process for converting the waste or used metalized polyester (PET) film into recycled PET (RPET) as a starting raw material for various utility products. Particularly, the present invention provides a process for the manufacturing of high quality strapping or monofilament yarn or sheets from the recycled metalized PET film.

This is a Continuation of application Ser. No. 14/781,194 filed Sep. 29,2015, which in turn is a national phase entry of PCT/IB2014/060126 filedon Mar. 25, 2014, which claims priority to IN 3342/DEL/2012 filed onMar. 31, 2013. The disclosure of the prior applications is herebyincorporated by reference herein in its entirety.

FIELD OF INVENTION

The present invention relates to a process for converting the waste andused metalized Polyester (PET) film into recycled PET (RPET) as astarting raw material for various utility products. Particularly, thepresent invention provides a process for the manufacturing of highquality strapping or monofilament yarn or sheets from the recycledmetalized PET film.

BACKGROUND AND PRIOR ART OF THE INVENTION

It is known that metalized PET films provide optimal solution for highoxygen and general gas barrier levels, aroma and flavor retention. Themetallization of PET film also results in significant improvement inwater vapor barrier. Metalized PET film is proven to achieve specialoptical properties or a metal look for decorative applications indiffusion of gases and flavor through the film. Although metalized PETfilm market continues to grow, there are no established sustainablesolutions to recover and recycle post-consumer and postindustrialmetalized PET films waste or any application of this material. While PETrecycling industry has been established for several decades and acceptedas the most leading recycled material, metalized PET films are discardedas waste and ends up in the landfill. The growing consumer awarenesstowards recycling of plastics demands requires creativity in recyclingof metalized PET films and its subsequent suitable applications. Thereare no known commercially existent metalized PET films recyclingfacilities in the world.

In order to increase the life cycle and reduce the carbon footprint,metalized PET films needs to be recycled effectively and efficiently.However, there are numerous issues that make recycling of PET filmsdifficult. The intrinsic viscosity (also known as I.V.) of metalized PETfilm is typically less than 0.6 dl/g making it unsuitable for manyapplications such as sheet extrusion/thermoforming and mono filamentyarn after recycling. Mechanical properties of PET films with 0.6 dl/gare very inferior and consequently limit its potential application afterrecycling. The color and clarity of recycled metalized film poseschallenges in clear applications. The increased haze and B value(yellowness) of metalized PET film makes it unattractive for mostapplications.

Unlike, PET bottles recycling, there are no established collectioncenters or material recovery facilities for PET films. Secondly, lack ofconsumer education, awareness and consequent participation for therecyclability of metalized films makes it difficult to be collected andrecycled even from an industrial source. The absence of definitive anddesired sources for collection of metalized PET films makes a poorbusiness case for the technology to be designed for this material.

The other reason for lack of Metalized PET film includes unknown scienceof washing Metalized PET films. The use of conventional PET recyclingtechniques, including hot washing with proven alkaline cleaners,de-foamer additives and other additives are yet to be proven effectivefor washing and removing Aluminum layer and other contaminates fromMetalized PET films. The effect of such additives and washing methods isunknown in public domain.

In view of the above-said challenges and keeping environment safety intoconsideration the applicant of the present invention comes out with aprocess for converting used/waste metalized PET film into recycled PETas a starting raw material for various utility products. Hence, anenvironmental friendly process for recycling of metalized PET film isdeveloped to produce recycled PET pellets with enhanced physical,mechanical, optical and aesthetic properties. The physical, mechanicaland aesthetic properties of the straps, yarn, and sheet as produced fromthe recycled metalized PET are comparable to virgin PET pellets used forthe same application. This is evident from the Table 6 & 7.

OBJECTS OF THE INVENTION

The primary objective of the present invention is to provide a processfor converting the waste and used metalized PET film into recycled PETas a starting raw material for various utility products.

Another objective of the present invention is to provide a process forrecycling of metalized PET film.

Yet another objective of the invention is to provide a process for themanufacturing of high quality strapping or monofilament yarn or sheetsfrom the recycled metalized PET film.

SUMMARY OF THE INVENTION

The present disclosure is directed to a process for recycling ofmetalized PET film. Furthermore, the present invention provides aprocess of manufacturing high quality PET Straps, PET monofilament yarn,opaque PET sheet and PET fiber as obtained from the recycling ofmetalized PET film. The present disclosure is also directed at optionalwashing process of metalized PET film to obtain clear PET films thatcould be used for obtaining PET which could be used for making PETfiber, PET films and clear PET Sheets as well in addition to PET strapsand PET monofilament yarn.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1: Graphic representation of recycling process

FIG. 2A: Microscope Analyses of pellet sliced with degassing

FIG. 2B: Microscope Analyses of pellet sliced without degassing

BRIEF DESCRIPTION OF THE TABLES

Table 1: Indicative IV requirements for most PET applications

Table 2: Key processing parameters during the recycling process

Table 3: The test results for degassing and without degassing

Table 4: Properties of clear recycled PET pellets (after washing) andmetalized recycled PET pellets after extrusion

Table 5: Properties of clear recycled PET pellets (after washing) andmetalized recycled PET pellets after SSP

Table 6: PET Straps from recycled metalized film without any anti-splitadditive

Table 7: PET Straps made from virgin PET resin without anti-splitadditive

Table 8: PET Straps from recycled metalized film with anti-splitadditive-larger cross section

DETAILED DESCRIPTION OF THE INVENTION

While the invention is susceptible to various modifications andalternative forms, specific aspect thereof has been shown by way ofexample and will be described in detail below. It should be understood,however that it is not intended to limit the invention to the particularforms disclosed, but on the contrary, the invention is to cover allmodifications, equivalents, and alternative falling within the spiritand the scope of the invention.

The Applicants would like to mention that the examples are mentioned toshow only those specific details that are pertinent to understanding theaspects of the present invention so as not to obscure the disclosurewith details that will be readily apparent to those of ordinary skill inthe art having benefit of the description herein.

The terms “comprises”, “comprising”, or any other variations thereof,are intended to cover a non-exclusive inclusion, such that a processthat comprises a list of components does not include only thosecomponents but may include other components not expressly listed orinherent to such process. In other words, one or more elements in asystem or process proceeded by “comprises . . . a” does not, withoutmore constraints, preclude the existence of other elements or additionalelements in the system or process.

Accordingly, the present invention relates to a process of convertingwaste or used metalized PET film to obtain recycled PET pellets suitableto produce PET Straps, monofilament yarn and PET Sheets comprising stepsof:

-   -   (i) collecting waste or used metalized PET film;    -   (ii) obtaining crushed film or flakes by reducing the size of        waste or used metalized PET film either before or after washing        by a grinder or granulator or by cutter-compactor;    -   (iii) washing the film of step (i) and/or crushed film or flakes        of step (ii) in hot water bath or in alkaline or in alkali        solution having concentration in the range of 0.5 to 3% in water        solution at room temperature to 90° C.;    -   (iv) densifying the film or flakes of step (iii) in a        agglomerator to increase the bulk density of the film or flakes;    -   (v) feeding thus obtained film or flakes of step (iv) into an        extruder for devolatilizing, homogenizing and converting the        same into melt;    -   (vi) conveying the melt of step (v) into a pelletizer to obtain        recycled PET pellets having intrinsic viscosity less than 0.55        dl/g;    -   (vii) increasing intrinsic viscosity of the pellets obtained in        step (vi) from 0.55 dl/g to 1.0 dl/g by solid state        polymerization or by chain extenders or by Erema's Vacurema        technology to obtain desired recycled PET pellets suitable for        making high quality strapping or monofilament yarn or sheets.

In other embodiment of the present invention the process of cleaningwaste or used metalized PET film, the alkaline solution is caustic sodahaving concentration in the range of 0.5 to 3 wt./v %, preferably in therange of 1 to 2 wt./v % at room temperature to 90° C. preferably at60-85° C.

In yet another embodiment of the present invention the process ofconverting waste or used metalized PET film to RPET pellets, themetalized PET film is agglomerated and extruded, pelletised andintrinsic viscosity is enhanced in a solid state polymerization processfrom 0.55 dl/g to 1.0 dl/g, preferably from 0.70 dl/g to 0.84 dl/g.

In yet another embodiment of the present invention the process ofconverting waste or used metalized PET film to RPET pellets the chainextenders such as di-functional or multi-functional chemical compoundsare used to enhance intrinsic viscosity.

In yet another embodiment of the present invention a high qualitystrapping or monofilament yarn or sheets are obtained from the recycledPET pellets.

In yet another embodiment of the present invention in PET strappingoptionally additives such as coloring agents or anti-splitting agents orcombination thereof are added.

In yet another embodiment of the present invention in PET strapping thecoloring agents such green or blue coloring agents or combinationthereof are added for decreasing yellowness index in the strap.

In yet another embodiment of the present invention in PET strapping theanti-splitting agents are added to improve tenacity of recycled PET andhelps in reducing the splitting of strap.

In yet another embodiment of the present invention the PET strapping isprepared by extrusion process at temperature in 270-295° C. range withsingle or multiple member of tapes wherein stretch ratio is in the rangeof 5:1 and cooling is carried out without turbulence, at temperature upto 40° C., maintaining the distance of 10 to 15 cm between die andsurface of cooling bath.

In yet another embodiment of the present invention the PET strapping isstretched by stretching in two stages where lowest possible stretchratio is kept in the first stage and the highest possible ratio is keptin the second stage.

In yet another embodiment of the present invention the PET strappinghaving tensile strength in the range of 472 N/mm² to 485N/mm² andelongation in the range of 12.1% to 12.4%.

In yet another embodiment of the present invention the PET strappingwherein the tensile strength and elongation are similar to that ofstraps produced from virgin PET pellets.

The process involved in recycling of PET film is described below indetail and in FIG. 1.

Collection of Metalized PET Film Waste

Various collection mechanisms can be used in order to improve the bulkdensity of the film as well as to ensure that minimum contaminationoccurs in the storage, material handling and transportation of themetalized metalized film. These include baling and shrink wrapping ofthe films and compaction techniques.

Size Reduction

The collected material may be size reduced either before or after thewashing process using a grinder or granulator. It may also be achieveddirectly in the cutter-compactor or the agglomerator as explained underthe extrusion process. Size reduction facilitates further processing ofthe material.

Washing of Metalized PET Films

The metalized PET film can be washed in a hot washing water bath tank orat room temperature with preferred level of an alkaline solution, suchas a solution containing caustic soda or in a solvent such as ahydrocarbon solvent. The desired level of caustic soda in the range of0.5 to 3% in a water solution at room temperature to 90° C. or any othersuitable alkali solution. Keeping the metalized film in 1% caustic sodasolution and 80-85° C. water temperature removed aluminum within fewseconds. The time required to remove aluminum from the metalized PETfilm for similar caustic soda solution was two minutes at roomtemperature water. The aluminum completely dissolves and the water actsas an acid. The aluminum layer from metalized PET film is removed andclear PET film is obtained after multiple washing stages varying from 2to 10 times.

One notable aspect of the washing of metalized PET film revealed thatreaction time and caustic solution did not adversely affect theintrinsic viscosity of the metalized PET films. The IV of the filmremained unchanged regardless of caustic soda and residence time in thewater tank.

The process of washing is optional in nature and helps in making theend-material clear as compared to silver metallic gray color of unwashedmaterial.

The washing process also helps in removing dust and other foreignparticles that get collected along with the waste metalized film duringthe process of storing, material handling and transportation. Otherprocesses to remove external impurities are floatation or sedimentationprocess and cyclone separation and/or magnetic and electrostaticseparation of metals.

Extrusion of Metalized PET Film

The process of the present invention includes use of cutter-compactortechnology that connects to a continuously filled pelletizing extruder.The washed or unwashed metalized PET films are fed into thecutter-compactor where the material is cut, mixed, heated, dried (toremove moisture and prevent the undesirable hydrolytic degradation)densified and buffered. This densification process can also be achievedusing an agglomerator which essentially performs the same function ofcompacting and increasing the bulk density of the material. The dried,compacted metalized PET film is fed into the plasticating extruder wheredevolatilization and homogeneous mixing takes place. The PET melt isthen cleaned in the self-cleaning filter. Following this, the melt isconveyed pelletizer to obtain uniform and consistent recycled PETpellets.

During the extrusion process, various additives may be added to modifythe properties of the PET pellets. These could be in the nature ofcolours or chain extenders or other functional additives. In oneembodiment, green colour was added to the waste metalized PET filmduring the extrusion process to achieve green colour recycled PETpellets.

The metalized PET film converted into PET pellets has an intrinsicviscosity (I.V.) of about 0.56 to 0.62 dl/g. The mechanical propertiessuch as impact strength, tensile strength, flexural modulus andelongation are very poor at such a low I.V. range of 0.56 to 0.62. Ascan be observed from the table below that very few PET applications arethere for low IV materials.

TABLE 1 Indicative IV requirements for most PET applications PETApplication IV (dl/g) PET Bottles 0.75-0.84 PET Sheets 0.64-0.78Bixially-oriented PET Films >0.60 Monofilament Yarn 0.65-1.50Partially-oriented Yarn 0.62-0.70 PET Staple Fiber 0.58-0.70 PET Straps0.70-0.90

IV Enhancement Process

In order to improve the mechanical properties and make it suitable forcommercial applications, the recycled PET pellets I.V. has to beincreased significantly. For example, in one embodiment, the intrinsicviscosity is increased through a solid state polymerization process 0.56to 0.84 dl/g. In one more instance the intrinsic viscosity is increasedto 0.65 dl/g. To achieve the IV increase the following processes wereused:

-   -   a. Solid State Polymerisation (SSP) in a tumble dryer or vacuum        reactor. The rate of I.V. increase depends on the SSP process        parameters and starting I.V. of the input material. In one        embodiment, the pellets are introduced into a reactor (SSP        reactor) which is subject to heat and vacuum to maintain an        inert environment. Alternatively, an inert gas such as Nitrogen        may be introduced to achieve the same objective. The pellets are        kept in the reactor at temperatures ranging from 205 to 230° C.        for a period of 4 hours to 30 hours. In another embodiment, the        pellets are first crytallised by pre-heating them at        temperatures ranging from 160 to 180° C. and thereafter placing        them in the SSP reactor. The process of Solid State        Polymerisation also changes the form of the pellets from        Amorphous to Crystalline which is easier to process in the        end-applications.    -   b. Use of chain extenders can be made to increase the IV by up        to 20% of the input I.V. This involves the use of di-functional        or multi-functional use of chemical compounds aimed at        rebuilding molecular weight and physical properties of degraded        thermoplastics by bridging their functionally terminated chains,        through a reaction known as “chain extension”. These reactions        are normally carried out in the melt phase of the polymer during        the extrusion process. There is normally a limitation to the        extent that the chain extenders can be used in a beneficial        manner.    -   c. Use of Erema's Vacurema technology. Here the densified        material is subject to reaction in a vessel to enhance the IV        prior to the extrusion process. The maximum IV increase in this        process normally is 10%. The inventor agglomerated the metalized        film and ran the material through vacurema process in which the        IV was enhanced. Thereafter, the material was extruded to make        pellets which would be quite suitable for making PET straps. By        this technique it was able to increase the IV by 19% as compared        to a maximum of 10%.

Solid State Polymerisation process has been disclosed in the followingU.S. Pat. Nos. 3,586,647, 3,657,388 and 3,969,324. In the above patents,the processes are directed to increasing the molecular weight ofprepolymers made from virgin materials. However, the present disclosurereveals the increase in intrinsic viscosity of the polymer chips madefrom recycled materials including metallised polyester film.

Applications

In the present invention a high quality strapping or monofilament yarnor sheets are obtained from the recycled PET pellets.

PET Straps

PET Strapping is made by extrusion process with single or multiplenumbers of tapes with required width. A de-humidifying dryer is used asit reduces moisture to less than 40 ppm required for trouble freeprocessing & achieving physicals. The strap is made by a process inwhich extruded strand of PET is subjected to plurality of stretchingsteps with final stretch ratio of around 5:1. Machine consists of asingle screw/twin screw extruder and die is made as per general rules ofstreamlined polymer flow: no dead corners, short dwell-time in die &homogeneous temperature all over the die.

Cooling is done by water at temperature of 35-40° C. The water must moveslowly i.e. ‘no turbulence’. A critical parameter to decrease splittingis a distance (air gap) of 10 to 15 cm between die and surface ofcooling bath to be maintained. The total stretching is to done in twostages. The lowest possible stretch ration is kept in the first zone andthe highest possible ratio in the second zone. A light ‘knurling’ isdone for a tight grip in handling and avoiding a slippage in usage.There is an optional facility of roto grauve printing at the end of theline.

A typical line will have screw, thermo regulated zones, metering pump,die head group, water cooling tank, slow stretching draw stand,diathermic oil heating unit (2 nos.) air stretching oven, faststretching draw stand, embossing and annealing unit, haul-off draw sandand a volumetric dosing system on main extruder. The strap machinewherein PET flakes can be used comes with a crystallising system and ade-humidifier for crystallised pellets.

Screw Geometry & Process Parameters for producing PET strapping whereinL/D ratio is in the range of 24:1 to 32:1, compression ratio: 1:2 to1:3, recommended temperature range is 270-290° C. In order to preventdegradation, polymer temperature should not exceed 310° C. andpreferably kept below 300° C. Additives such as colorants are added torecycle PET pellets (normally green). The neck piece is mounted on feedthroat to which dosing unit is attached. In order to further improve thephysical properties, anti-splitting additives are added, which primarilyimprove tenacity of recycled PET. In case of PET it helps in reducing itthe splitting of strap observed in processing and use, especially whenhigher quantities of recycled PET is used. This results in reducedfibrillation & increased melt strength.

In one embodiment the high I.V. pellets from metalized film are used forextrusion of PET straps with tensile strength in the range of 472 N/mm²to 485 N/mm²) and elongation in the range of 12.1% to 12.4%. Theextruded PET straps can be used for various industrial applications suchas parcel packaging, natural and artificial fibers (such as cotton balesand yarns), brick industry and packaging of logs etc. PET straps can beextruded in silver metallic gray color from unwashed metalized PET filmmanifesting natural aluminum color in PET strapping. PET straps obtainedfrom clear SSP pellets from metalized PET film can be colored inconventional green strapping by adding the appropriate green colorconcentrate. In another instance, a colouring agent such as green colourhas been added directly to the silver metallic gray pellets producedfrom unwashed metalized PET film to achieve green colour PET straps.

Monofilament Yarn

In another embodiment SSP pellets of metalized PET film can be extrudedfor mono filament yarn applications with adequate mechanical properties.Extrusion of monofilament requires large number of process steps asmonofilament properties are determined by many factors such as therheological properties during extrusion and draw down of monofilamentafter they emerge from die-plate holes. The rheological properties aredependent on the SSP process of metalized PET film pellets.

PET Sheets

In another embodiment coloured PET sheets can be directly extruded fromthe IV enhanced recycled PET pellets/pellets. In accordance with thepresent disclosure during sheet extrusion process using PET pellets madefrom washed metalized film recycling process, an opticalbrightener/tinting agent like (water blue color concentrate) is added tonegate the yellowness and improve the B value of extruded sheet. Theextruded sheet appears sparkling blue and masking dull yellow appearanceof typical RPET sheet. The extruded PET sheet can be used in variousthermoforming packaging applications.

In another embodiment of the invention, pellets from recycled metalizedPET films can be used in indirect food contact application by using thepellets in the middle layer of sandwich type co-extrusion structure. Inanother aspect of the invention the pellets of metalized PET can be usedfor direct food contact application by using a de-contamination processunder vacuum and for specific time and temperature that reduces harmfuldietary substance below FDA thresholds of less than one part perbillion. The decontaminated pellets can be extruded into PET sheet andused for various thermoforming packaging applications.

PET fiber

PET fiber can be extruded from the pellets/pellets obtained from themetalized PET film. Since the IV requirement of PET fiber is low, thisapplication can use both the pre-SSP and post-SSP pellets in itsproduction process.

EXAMPLES

The following examples are given by way of illustration of the presentinvention and therefore should not be construed to limit the scope ofthe present invention. Recycling of Aluminium coated PET film (MetalizedPET film)

Following were measured to observe the quality of the recycled PETgranules made from Metalized PET film:

-   -   performance of the recycling-line    -   test with standard-degassing    -   test without degassing

FIGS. 2A and 2B represent the Microscope Analysis of pellets sliced withdegassing (FIG. 2A) and pellets sliced without degassing (FIG. 2B), andit is observed with high vacuum there was less IV-decrease. The test ofdegassing was performed with standard degassing method.

From the Tables 6 to 8 it is evident that the important mechanicalproperties of PET straps produced from recycled Metalized PET pelletsare comparable to the virgin PET pellets. The strength and othermechanical properties are direct dependent on the cross-section of thestrap. While, higher cross-section results in higher break loadstrength, the tensile strength of different sizes can be compared.Hence, by recycling used/waste metalized PET by the process as disclosedin the present invention useful PET pellets can be produced and used asa starting raw material for various utility products.

ADVANTAGES OF THE INVENTION

A waste metalized PET film is recycled and reduces the environmentaleffect of using virgin PET.

A waste metalized PET film is recycled and converted into PET pelletswith enhanced intrinsic viscosity.

A recycled PET pellets are used for manufacturing high quality strappingor monofilament yarn or sheets with improved mechanical properties.

The strap produced by recycling of metalized PET film showed a tensilestrength in the range of 472 to N/mm² to 485 N/mm² and elongation atbreak in the range of 12.1% to 12.4%. Considering that the raw materialused has been recycled, the above values obtained are very good.

TABLE 2 Key processing parameters during the recycling process PROCESSWith Without PARAMETERS Unit Degassing Degassing Die plate [mm] 10 × 4.510 × 4.5 number of pelletizer knives [pcs] — — ØAG-load [%]  81  81extruder speed [rpm] 100 110 diff back flush pressure [bar]  90  90speed pelletizer [rpm] 80 rpm 80 rpm strand strand temp. extruder [° C.]270 270 temp. degassing [° C.] 270 270 temp. filter [° C.] 280 290 temp.pelletizer [° C.] 280 300 Water temp. pelletizer [° C.]  18  18

TABLE 3 The test results for degassing and without degassing No.Materials Explanation IV INPUT-Material 1 Metalized PET Film Input fromshredder 0.567 2 Metalized PET Film Input film 0.583 RPET pellets 1 RPETpellets from Metalized PET without Degassing 0.540 Film 2 RPET pelletsfrom Metalized PET with Degassing 0.547 Film

TABLE 4 Properties of clear recycled PET pellets (after washing) andmetalized recycled PET pellets after extrusion Intrinsic Viscosity dl/gAsh wt % Test Method S. No. Material ASTM-D 4603 ASTM D-5630 A RecycledPET Clear Pellets 1 Sample 1 0.585 0.024 2 Sample 2 0.559 0.039 3 Sample3 0.551 0.045 4 Sample 4  0.5780 0.040 5 Sample 5 0.588 0.035 Range0.55-0.60 0.010-0.050 B Recycled PET Metallic Pellets 1 Sample 1 0.5300.565 2 Sample 2 0.543 1.478 3 Sample 3 0.563 1.207 4 Sample 4 0.5681.056 5 Sample 5 0.584 0.772 Range 0.52-0.60 0.5-1.5

TABLE 5 Properties of clear recycled PET pellets (after washing) andmetalized recycled PET pellets after SSP Intrinsic Viscosity dl/g Ash wt% Test Method S. No. Material ASTM-D 4603 ASTM D-5630 A Recycled PETClear Pellets 1 Sample 1 0.847 0.033 2 Sample 2 0.844 0.034 3 Sample 30.853 0.030 4 Sample 4 0.824 0.029 5 Sample 5 0.839 0.035 Range0.82-0.86 0.010-0.050 B Recycled PET Metallic Pellets 1 Sample 1 0.7950.945 2 Sample 2 0.850 0.980 3 Sample 3 0.806 1.446 4 Sample 4 0.7861.093 5 Sample 5 1.01  0.990 Range 0.78-1.01 0.5-1.5

TABLE 6 PET Straps from recycled metalized film without any anti-splitadditive Cross Tensile Section Break Load Strength Elongation SO F maxRm −F max Sample Nr mm² N N/mm² % 1 5.43 2569.46 473.41 12.10 2 5.432613.71 481.56 12.22 3 5.30 2519.41 475.62 12.23 4 5.38 2611.93 485.7812.44 5 5.48 2539.65 463.59 12.32 6 5.45 2518.43 462.16 12.41 7 5.472572.58 470.22 12.18 8 5.44 2518.24 462.74 12.28 Mean 5.42 2557.93471.89 12.27 Min. 5.30 2518.24 462.16 12.10 Max. 5.48 2613.71 485.7812.44

ASTM D-3950 is used for testing the break load, tensile strength andelongation

TABLE 7 PET Straps made from virgin PET resin without anti-splitadditive Cross Tensile Section Break Load Strength Elongation SO F maxRm −F max Sample Nr mm² N N/mm² % 1 5.51 2450.65 444.40 9.26 2 5.502643.41 480.62 8.66 3 5.46 2582.49 473.29 10.40 4 5.48 2428.95 443.389.67 5 5.52 2586.68 468.45 9.66 6 5.43 2531.24 465.75 9.55 7 5.522543.03 460.55 8.10 8 5.54 2326.08 419.61 7.88 Mean 5.50 2511.57 457.019.15 Min. 5.43 2326.08 419.61 7.88 Max. 5.54 2643.41 480.62 10.40

ASTM D-3950 is used for testing the break load, tensile strength andelongation

TABLE 8 PET Straps from recycled metalized film with anti-splitadditive- larger cross section Cross Tensile Section Break Load StrengthElongation SO Fmax Rm −F max Sample Nr mm² N N/mm² % 1 9.09 4281.04471.12 12.33 2 9.21 4443.22 482.43 12.09 3 9.11 4360.81 478.75 12.23 49.16 4344.11 474.28 12.55 Mean 9.14 4357.30 476.65 12.30 Min. 9.094281.04 471.12 12.09 Max. 9.21 4443.22 482.43 12.55

ASTM DIN 51220 is used for testing the break load, tensile strength andelongation

1. A process of converting waste or used metalized polyethyleneterephthalate (PET) film to obtain recycled metalized PET pelletssuitable to produce PET straps, monofilament yarn, and PET sheets, themethod comprising: (i) collecting waste or used metalized PET film; (ii)obtaining crushed film or flakes by reducing the size of the waste orused metalized PET film by a grinder or granulator or by cuttercompactor; (iii) washing the film of step (i) and/or crushed film orflakes of step (ii) in a hot water bath or in an alkaline or alkalisolution having a concentration in the range of 0.5 to 3% in watersolution at a temperature of from room temperature to 90° C.; (iv)densifying the film or flakes of step (iii) in an agglomerator toincrease the bulk density of the film or flakes; (v) feeding the thusobtained film or flakes of step (iv) into an extruder fordevolatilizing, homogenizing, and converting the same into melt; (vi)conveying the melt of step (v) into a pelletizer to obtain recycledmetalized PET pellets having an intrinsic viscosity less than 0.60 dl/g;and (vii) increasing the intrinsic viscosity of the pellets obtained instep (vi) to a value of up to 1.00 dl/g by solid state polymerization ofthe recycled metalized PET, wherein the thus obtained recycled metalizedPET pellets are suitable for making high quality strapping ormonofilament yarn or sheets.
 2. The process as claimed in claim 1,wherein the alkaline solution is a caustic soda having a concentrationin the range of 1 to 2 wt./v % at a temperature of 60-85° C.
 3. Theprocess as claimed in claim 1, wherein the metal in the metalized filmis aluminum.
 4. The process as claimed in claim 1, wherein the thusobtained recycled metalized PET pellets of step (vii) are suitable formaking high quality strapping or monofilament yarn or sheets that aremade up of up to 100% of said pellets.
 5. A PET strapping ormonofilament yarn or sheets produced from the recycled metalized PETpellets obtained by the process as claimed in claim 1.